1. Field of the Invention
The present invention relates to a package substrate, and more particularly to a package substrate having a plating bar reserved therein for plating ball pads of the package substrate.
2. Description of the Prior Art
High efficiency, high integration, low cost and miniaturization are all performances desired in designing and manufacturing electrical products, for achieving said requirements, IC package technology also develops toward miniaturization and compactness. Besides familiar Ball Grid Array Package (BGA Package), Chip-Scale Package (CSP) and Flip Chip Package (F/C Package), for the sake of further incorporating multi-function chip modules, a stack package technology is recently provided to improve the whole package density via stacking several chips together.
For the sake of mounting different type of chips in one substrate, a hybrid substrate is a commonly used carrier in stacking package. Usually, the hybrid substrate has many different type of electrical contacts to provide suitable electrical connecting manners for different chips. Taking a hybrid substrate conjuncting a Surface Mount Technology (SMT, i.e. Flip Chip Bonding) and a wire bonding technology (W/B Technology) as an example, the hybrid substrate has both finger contacts for wire bonding and bonding pads for surface bonding. Furthermore, the hybrid substrate has a plurality of first ball pads for electrically connecting with said finger contacts and a plurality of second ball pads for electrically connecting with said bonding pads on the bottom, used to provide different signal transfer paths.
In a manufacture process of a conventional hybrid substrate, it not only needs to form an anti-oxidation layer on the finger contacts, but also needs to form a same anti-oxidation layer on the first ball pads and the second ball pads. However, the bonding pads need not to be plated to form an anti-oxidation layer, and the high density distribution of the bonding pads makes it difficult to dispose plating bars therebetween. Thus, when the second ball pads connected to said bonding pads do not connect with said plating bars, the second ball pads are unable to be simultaneously plated together with the finger contacts and the first ball pads. Therefore, it needs to perform additional anti-oxidation treatment or add more complex producing process, this will influence the production efficiency and manufacturing yield of the product.